Transimpedance amplifiers are useful in many applications. One approach to designing transimpedance amplifiers (TIAs) is to directly connect the amplification stages to the power supply rail (e.g., V_CC). In this approach, the transimpedance amplifiers do not have any circuit for power supply regulation of the amplification stages. One disadvantage of these types of TIAs without power supply regulation is that the TIA exhibits poor power supply rejection.
Another approach to designing transimpedance amplifiers (TIAs) is to utilize a shunt regulator for improving the power supply rejection of the TIA. As can be appreciated, although TIA with a shunt regulator provides improved power supply rejection as compared with the first approach, additional current is needed to maintain internal supply regulation of the amplifier stages. This additional current does not contribute to the signal bandwidth of the amplifier stages and is essentially wasted in order to obtain good power supply rejection.
Another example of a design approach for TIAs is set forth in a publication entitled, “A Novel CMOS Transimpedance Amplifier for DVD Application,” Sau-Mou Wu, Chung-Yuan Chen, ECCTD'03—European Conference on Circuit Theory and Design, Sep. 1-4, 2003, Cracow, Poland, pages 233-236.
One disadvantage of current three-stage transimpedance amplifier circuit architecture is that the architecture diverts current from the main transistor amplifier to the gm-connected load. Consequently, relatively more current is required to produce a required gain to satisfy performance requirements of the amplifier.
A second disadvantage of current three-stage transimpedance amplifier circuit architecture is that the architecture employs a regulator on the internal rail for noise rejection, but the regulator requires shunting additional current to ground through a separate amplifier. Consequently, this design requires more current and also requires additional circuit elements to implement the separate amplifier.
Other challenges in the design of transimpedance amplifier circuit include reducing the current consumption of the amplifier, which in turn reduces the power consumption of the circuit, while increasing the bandwidth of the transimpedance amplifier.
Based on the foregoing, there remains a need for a transimpedance amplifier with a self-biased regulator that overcomes the disadvantages set forth previously.